We believe you will need this sensor especially you are in busy city where air pollution is high, example Beijing. This is particularly true in the case of Malaysia where we might have serious haze condition a result from our neighboring country open forest burning. And for Measuring air quality includes the necessity to determine the amount of dust or particulate matter (PM) in the air. Dust is not so bad but really small particles, 2.5µm and 10µm in diameter, can penetrate the lungs causing all sorts of health problems. The measurement of these particles are often called 2.5PM and 10PM and they are measured in micro-grams per cubic meter of air (µg/m3).
This Honeywell HPM32322550 sensor uses laser based light scattering to detect both 2.5µm and 10µm sized particles. It has an integrated fan to maintain constant airflow across the sensing chamber. The sensor does all the internal processing and temperature compensation and outputs both measurements over an easy to use serial interface every second.
The sensor itself comes with a tiny 8-pin connector which is difficult to interface, therefore we have custom made a cable and a board that provide proper level shifter and extend it out to Grove standard connector. This sensor have very strict voltage tolerance, you need to make sure the voltage source is 5.0V ± 0.2V! Yup, we have tested with 4.7V and the sensor reading is not stable. But the weird feature is the UART interface is 3.3V TTL. Therefore, it cannot be interface directly to Arduino, a proper voltage level shifter is needed, hence the breakout board. We have added some extra features to the breakout board, with a OLED (separately), it can display the PM2.5 and PM10 reading, just power it with a USB microB (Power bank, laptop USB).
There is a auto report mode which enable the sensor to report the PM reading every one second. Only three connections (5V, GND, RX) are required if it is being configured in this mode. But if you want to send commands to the module you’ll need a fourth wire (TX). We’ve prepare the library for Arduino which you can grab it from here.
The sensor requires 5V to operate so we recommend using this with a Arduino UNO with Grove shield or other platform that can provide a good 5V at 80mA.
Walking and/or movement of the sensor will cause airflow variations across the sensing chamber but the variance is not estimated to have significant impact on the measurements.
Picture below shows how to put the OLED Display in a correct position.
If you see from the isometric view after you soldered it in the correct orientation, it should be like this.
Note: Please note that OLED Display is not included in the packing list. You can get the OLED here.
- Voltage: 5V
- Operating Principle: Laser Scattering
- Output data: PM2.5 in ug/m3 (PM10 with additional programming via UART)
- Current: <80mA (laser/fan on), < 20mA during sleep (laser/fan off)
- Precision: 0.0 to 1,000 µg/m3
- Interface: UART (5V at GROVE), 9600 baud, 8B, 1 stop bit, no parity
- Accuracy: +/- 15µg/m3, +/-15% at upper threshold of 999µg/m3
- Software controlled sleep and wake
- Operating hours: 20,000 hours
- Honeywell HPM32322550 Datasheet
- Getting Started Guide for this module
- Example sketches to get your started
- Good Wikipedia article on particulates